A radio control system uses radio waves to remotely control a target to be controlled (Hereinafter, referred to as a control target) at a remote location. In this radio control system, an operator controls, with a transmitter, the control target such as a model airplane, a model helicopter, a model car, or the like. The system has been used in hobby applications to compete in the field of control technology in regards to speed and acrobatics, or in applications of industrial equipment to control a control target such as a lawn mower or a crane.
The transmitter of the radio control system is a device for controlling a control target, and includes a transmitting unit which transmits a steering signal corresponding to the operation of the operator.
The control target includes a receiving unit which receives the steering signal, and the receiving unit sends a control signal based on the steering signal. The control signal controls a power unit such as a motor or an engine, and a drive control device such as a servo device which performs a drive control of each key or throttle of the engine, and a gyro device which maintains the stability of an aircraft.
Regarding the control of the servo device, for example, Japanese Patent Laid-open Publication No. 2000-024334 discloses a technology in which an adjustment value is changed at a switching point that has been arbitrarily set, the adjustment value for determining a relationship between the operation amount of a manipulation member provided in the transmitter and the operation amount of the servo device.
Further, regarding the control of the engine that has been conventionally used in the power unit, for example, Japanese Utility Model Registration No. 3079600 discloses a technology in which the rotational speed of the engine is controlled using a manipulation lever, a switch and the like provided in the transmitter. Particularly, in this technology, the rotational speed of the engine promptly returns to an idling value that has been initially set when the switch is turned to ON after the engine has been stopped.
Recently, in the field of the radio control system for hobby applications, a motor is often used as a power unit in a control target such as a model airplane or a model glider. The model airplane of the conventional radio control system usually uses an engine as a power unit, and the control method thereof is different from that of the motor.
For example, in a conventional control target of using an engine as a power unit, since restarting of the engine causes loss of fuel or troublesome operations after the engine is stopped, it is set to be in an idling state where the engine performs a minimum rotation when a lever for controlling the engine makes contact with one end of a movable range.
Alternatively, in the airplane or glider using a motor as a power unit, one arbitrary manipulation member set by the operator is used to control the motor. When using a lever as the manipulation member, it is set such that the rotation of the motor is stopped when the lever makes contact with one end of its movable range, and the rotation of the motor is maximized when the lever is brought into contact with the other end thereof.
As described above, when the lever is operated to be in contact with one end of the movable range, the rotation of the motor serving as a power unit is stopped. Accordingly, the rotation of a propeller, which is provided in the control target, is stopped to change a load associated with the control target. Thus, the operation feels different from that of a control target using the engine as the power unit.
Further, in order to maintain the motor at a low rotational speed as in the idling state of the engine, the operator needs to maintain the manipulation member at an operation amount at which the rotational speed of the motor is suitable, which is difficult to require a very delicate operation.
Even in the case of using the motor as the power unit, there has been a demand for a control that can be achieved by the same operation (e.g., the control of the low rotational speed) as the control target using the engine as the power unit.